Figure 2.

Disease progress as affected by maternal CO₂ concentration (280, 440, 600 ppm) and plant type (P = pink flowering, W = white flowering) in 2006 and 2007 (Case 2). Inserts show disease-progress affected by maternal CO₂ only (Case 1). Disease severity was determined for each leaf and was subsequently added up for all leaves of a plant and expressed on a scale ranging between 0 and 1 (see Materials and Methods). Mean ± 1 SE, n = 3 model ecosystems. Non-identical letters indicate statistically significant differences among combinations of maternal CO₂ treatments and plant type (main panels) or among maternal CO₂ concentrations (inserts) as analyzed by the Tukey–Kramer HSD test (P ≤ 0.05 within mixed models, see Table 4). Sixty-three days after sowing in 2007, disease severity was significantly higher in 440-ppm progenies of plant-type W compared with all Type P progenies (Tukey–Kramer HSD test, P ≤ 0.05).